If $x \star y = 4x-6$ and $x \triangleright y = x+8y$, find $(-2 \star -4) \triangleright 4$.
Explanation: First, find $-2 \star -4$ $ -2 \star -4 = (4)(-2)-6$ $ \hphantom{-2 \star -4} = -14$ Now, find $-14 \triangleright 4$ $ -14 \triangleright 4 = -14+(8)(4)$ $ \hphantom{-14 \triangleright 4} = 18$.